<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>盒子圆角</title>
    <style>
      .div1 {
        background-color: red;
        width: 200px;
        height: 100px;
        border-radius: 30px;
      }
      .div2 {
        background-color: blue;
        width: 200px;
        height: 200px;
        border-radius: 100px;
      }
      .div3 {
        background-color: green;
        width: 200px;
        height: 100px;
        border-radius: 50px;
      }
    </style>
  </head>
  <body>
    <div class="div1">圆角</div>
    <div class="div2">正圆</div>
    <div class="div3">胶囊</div>
  </body>
</html>
